(1) Field of the Invention
The present invention relates to an adhesive film position detector and an adhesive film joining apparatus. Specifically, in one step of surface treatment for various substrates such as a semiconductor substrate and a glass substrate for use in a liquid crystal display device, the adhesive film position detector is used when an adhesive film is joined to a surface of a substrate. Herein, the adhesive film has a shape corresponding to a shape of the substrate.
(2) Description of the Related Art
Conventionally, there have been proposed various adhesive film joining apparatuses for joining, to a surface of a substrate, an adhesive film having a shape corresponding to a shape of the substrate. For example, JP 07-195527 A discloses an adhesive film joining apparatus having the following configuration. That is, a colored adhesive film joined to a transparent base tape is fed by film feed means, and then is detected by a film detection mechanism when arriving at a certain position. Based on a result of the detection, the film detection mechanism stops the feed of the base tape. Alternatively, the film detection mechanism detects deviations in the relative position and angle between the adhesive film and a substrate at the stop position. Thereafter, these deviations are corrected, so that the substrate and the base tape are fed in synchronization with each other. Thus, an adhesive film, which is separated from the base tape at a tape folding end, is joined to a surface of a substrate in succession.
In the adhesive film joining apparatus disclosed in JP 07-195527 A, the film detection mechanism includes a first reflective optical sensor for detecting an adhesive film while the film supply tape is fed. The film detection mechanism also includes a second reflective optical sensor in accordance with a size of the adhesive film to be used herein. At the time when a rear end edge of the adhesive film is detected by the second optical sensor, the feed of the film supply tape is stopped. Herein, this stop position is defined as a predetermined joining position.
The film detection mechanism also includes a CCD camera serving as detection means for detecting a positional deviation of the adhesive film. When the feed of the film supply tape is stopped, the CCD camera captures an image of the colored adhesive film. Then, the film detection mechanism detects the positional deviation by measuring a distance from a predetermined reference line to an end surface of the adhesive film.
However, the technique disclosed in JP 07-195527 A still has the following problem which can not be solved thereby.
In a case where an adhesive film is an optically transparent or semitransparent film, it is very difficult for the adhesive film joining apparatus disclosed in JP 07-195527 A to stably detect such an adhesive film through use of the optical sensor such as the reflective optical sensor. Since the base tape is of a transparent type, if the adhesive film joined to the base tape is of a transparent or semitransparent type, the optical sensor fails to recognize a difference between an amount of light reflected from the base tape and an amount of light reflected from the adhesive film. Consequently, there arises a problem that an adhesive film can not be stably set at the joining position.
In the technique disclosed in JP 07-195527 A, a positional deviation is detected through use of the CCD camera. However, in a case where an adhesive film to be used herein is of a transparent type or a slightly colored type, it is difficult to detect an end surface of such an adhesive film even with this detecting method. The CCD camera fails to clearly recognize a contrast between the transparent base tape and the transparent or slightly colored adhesive film. Consequently, the film detection mechanism fails to detect an end surface of the adhesive film. As a result, the film detection mechanism fails to measure a distance from the reference line to the end surface of the adhesive film. Moreover, the film detection mechanism fails to accurately detect a position of the adhesive film.